Video Piggy is one of around 25 million different YouTube video downloaders on the market today. Although it's not the best we've seen, it's certainly not useless and provides a simple interface and configurable conversion profiles that allow you to instantly transform the format of your downloaded video for use on your portable device such as an iPod, PSP or mobile phone.
Unfortunately the maximum video is just 320 x 240 and you don't get any options to tweak the audio or video quality. The program also only allows you to download the movie in its original format, although there are separate features for converting to WMV, MOV, and MPEG. As a result, Video Piggy is not bad, but there are plenty more YouTube downloaders that offer more features.